Hybrid electric vehicles (HEVs) have both an internal combustion engine and an electric motor which can alternately or in combination be used to propel the vehicle. A variety of different drive trains are used in hybrid vehicles. The present application relates to a parallel configuration in which the engine is connected to a dual clutch transmission, and where an electric machine is positioned downstream of the dual clutch transmission.
A problem facing such a vehicle configuration is how to rapidly start the engine under various vehicle operating conditions. One solution involves a dedicated engine starter motor, for example an integrated starter/generator, for cranking the engine. However, such a solution adds cost, weight, and in some examples, relying on a dedicated engine starter motor may not be desirable. As an example, under conditions where performance of the dedicated engine starter motor is degraded, if the engine is unable to be started via an alternative means, then vehicle propulsion may be limited to electric-only propulsion, which may thus limit vehicle operating range. In another example, if a change-of-mind event occurs during an engine shutdown, relying solely on the dedicated engine starter motor may result in less than desirable acceleration response times. In still another example, in a case where a vehicle operator steps off of an accelerator pedal (e.g. a lift-pedal event), if an onboard energy storage device is unable to accept further charge, and thus regenerative braking may not be utilized, it may be desirable to rapidly start the engine in a deceleration fuel shut off mode of operation for use in engine braking.
The inventors herein have recognized these issues, and have developed systems and methods to address the above issues. In one example, a method is provided, comprising cranking an engine of the vehicle by controlling a capacity of a clutch of a dual clutch transmission positioned downstream of the engine and compensating for driveline disturbance resulting from the cranking via controlling an electric machine positioned downstream of the dual clutch transmission under conditions where a vehicle speed is below a minimum vehicle speed threshold.
In another example, a method is provided, comprising cranking an engine of the vehicle by controlling a capacity of a clutch of a dual clutch transmission positioned downstream of the engine and compensating for driveline disturbance resulting from the cranking via controlling an electric machine positioned downstream of the dual clutch transmission under conditions where a vehicle speed is above a minimum vehicle speed threshold.
In this way, an engine may be started under varying operating conditions in a vehicle that includes a dual clutch transmission downstream of the engine, and where an electric machine is positioned downstream of the dual clutch transmission. In such examples, the electric machine may compensate for driveline torque disturbance during the engine starting procedure.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.